<?php

/**
 *
 * @desc  HTTP 请求类, 支持 CURL 和 Socket, 默认使用 CURL , 当手动指定
 *              useCurl 或者 curl 扩展没有安装时, 会使用 Socket
 *              目前支持 get 和 post 两种请求方式
 *
 * @example
 *
  1. 基本 get 请求:

  $http = new Http();         // 实例化对象
  $result =  $http->get('http://weibo.com/at/comment');

  2. 基本 post 请求:

  $http = new Http();         // 实例化对象
  $result = $http->post('http://someurl.com/post-new-article', array('title'=>$title, 'body'=>$body) );

  3. 模拟登录 ( post 和 get 同时使用, 利用 cookie 存储状态 ) :

  $http = new Http();         // 实例化对象
  $http->setCookiepath(substr(md5($username), 0, 10));        // 设置 cookie, 如果是多个用户请求的话
  // 提交 post 数据
  $loginData = $http->post('http://login.sina.com.cn/sso/login.php?client=ssologin.js(v1.3.19)', array('username'=>$username, 'loginPass'=>$password) );
  $result =  $http->get('http://weibo.com/at/comment');

  4. 利用 initialize 函数设置多个 config 信息

  $httpConfig['method']     = 'GET';
  $httpConfig['target']     = 'http://www.somedomain.com/index.html';
  $httpConfig['referrer']   = 'http://www.somedomain.com';
  $httpConfig['user_agent'] = 'My Crawler';
  $httpConfig['timeout']    = '30';
  $httpConfig['params']     = array('var1' => 'testvalue', 'var2' => 'somevalue');

  $http = new Http();
  $http->initialize($httpConfig);

  $result = $http->result;

  5. 复杂的设置:

  $http = new Http();
  $http->useCurl(false);      // 不使用 curl
  $http->setMethod('POST');       // 使用 POST method

  // 设置 POST 数据
  $http->addParam('user_name' , 'yourusername');
  $http->addParam('password'  , 'yourpassword');

  // Referrer
  $http->setReferrer('https://yourproject.projectpath.com/login');

  // 开始执行请求
  $http->execute('https://yourproject.projectpath.com/login/authenticate');
  $result = $http->getResult();

  6. 获取开启了 basic auth 的请求

  $http = new Http();

  // Set HTTP basic authentication realms
  $http->setAuth('yourusername', 'yourpassword');

  // 获取某个被保护的应用的 feed
  $http->get('http://www.someblog.com/protected/feed.xml');

  $result = $http->result;

 *
 * @from http://www.phpfour.com/lib/http
 * @since Version 0.1
 * @original author      Md Emran Hasan <phpfour@gmail.com>
 * @modify by       Charlie Jade
 */
class Http {

    /**  目标请求 @var string */
    var $target;

    /**  目标 URL 的 host @var string */
    var $host;

    /**  请求目标的端口 @var integer */
    var $port;

    /** 请求目标的 path @var string */
    var $path;

    /** 请求目标的 schema  @var string */
    var $schema;

    /** 请求的 method (GET 或者 POST)  @var string */
    var $method;

    /** 请求的数据  @var array */
    var $params;

    /**  请求时候的 cookie 数据  @var array */
    var $cookies;

    /**  请求返回的 cookie 数据 @var array  */
    var $_cookies;

    /** 请求超时时间, 默认是 25 @var integer */
    var $timeout;

    /** 是否使用 cURL , 默认为 TRUE @var boolean */
    var $useCurl;

    /**   referrer 信息 @var string */
    var $referrer;

    /** 请求客户端 User agent  @var string */
    var $userAgent;

    /**  Contains the cookie path (to be used with cURL) @var string */
    var $cookiePath;

    /**  是否使用 Cookie @var boolean  */
    var $useCookie;

    /** 是否为下一次请求保存 Cookie @var boolean */
    var $saveCookie;

    /** HTTP Basic Auth 用户名 (for authentication) @var string */
    var $username;

    /** HTTP Basic Auth 密码 (for authentication) @var string */
    var $password;

    /** 请求的结果集 @var string */
    var $result;

    /** 最后一个请求的 headers 信息  @var array */
    var $headers;

    /** Contains the last call's http status code @var string  */
    var $status;

    /** 是否跟随 http redirect 跳转  @var boolean */
    var $redirect;

    /** 最大 http redirect 调整数 @var integer */
    var $maxRedirect;

    /** 当前请求有多少个 URL  @var integer */
    var $curRedirect;

    /** 错误代码 @var string */
    var $error;

    /** Store the next token  @var string */
    var $nextToken;

    /** 是否存储 bug 信息 @var boolean  */
    var $debug;

    /** Stores the debug messages  @var array @todo will keep debug messages */
    var $debugMsg;

    /**  Constructor for initializing the class with default values. @return void   */
    public function __construct() {
        // 先初始化
        $this->clear();
    }

    /**
     * 初始化配置信息
     * Initialize preferences
     *
     * This function will take an associative array of config values and
     * will initialize the class variables using them.
     *
     * Example use:
     *
     * <pre>
     * $httpConfig['method']     = 'GET';
     * $httpConfig['target']     = 'http://www.somedomain.com/index.html';
     * $httpConfig['referrer']   = 'http://www.somedomain.com';
     * $httpConfig['user_agent'] = 'My Crawler';
     * $httpConfig['timeout']    = '30';
     * $httpConfig['params']     = array('var1' => 'testvalue', 'var2' => 'somevalue');
     *
     * $http = new Http();
     * $http->initialize($httpConfig);
     * </pre>
     *
     * @param array Config values as associative array
     * @return void
     */
    public function initialize($config = array()) {
        $this->clear();
        foreach ($config as $key => $val) {
            if (isset($this->$key)) {
                $method = 'set' . ucfirst(str_replace('_', '', $key));

                if (method_exists($this, $method)) {
                    $this->$method($val);
                } else {
                    $this->$key = $val;
                }
            }
        }
    }

    /**
     * 初始化所有
     *
     * Clears all the properties of the class and sets the object to
     * the beginning state. Very handy if you are doing subsequent calls
     * with different data.
     *
     * @return void
     */
    public function clear() {
        // Set the request defaults
        $this->host = '';
        $this->port = 0;
        $this->path = '';
        $this->target = '';
        $this->method = 'GET';
        $this->schema = 'http';
        $this->params = array();
        $this->headers = array();
        $this->cookies = array();
        $this->_cookies = array();

        // Set the config details
        $this->debug = FALSE;
        $this->error = '';
        $this->status = 0;
        $this->timeout = '25';
        $this->useCurl = TRUE;
        $this->referrer = '';
        $this->username = '';
        $this->password = '';
        $this->redirect = TRUE;

        // Set the cookie and agent defaults
        $this->nextToken = '';
        $this->useCookie = FALSE;
        $this->saveCookie = FALSE;
        $this->maxRedirect = 3;
        $this->cookiePath = 'cookies.txt';
        //$this->userAgent    = 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.63 Safari/535.7';
        $this->userAgent = 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.137 Safari/537.36';
    }

    /** 设置目标 @return void */
    public function setTarget($url) {
        $this->target = $url;
    }

    /** 设置 http 请求方法  @param string HTTP method to use (GET or POST)  @return void */
    public function setMethod($method) {
        $this->method = $method;
    }

    /** 设置 referrer URL @param string URL of referrer page @return void */
    public function setReferrer($referrer) {
        $this->referrer = $referrer;
    }

    /**  设置 User agent  @param string Full user agent string @return void */
    public function setUseragent($agent) {
        $this->userAgent = $agent;
    }

    /** 设置请求 timeout  @param integer Timeout delay in seconds @return void */
    public function setTimeout($seconds) {
        $this->timeout = $seconds;
    }

    /** 设置  cookie path (只支持cURL ) @param string File location of cookiejar @return void */
    public function setCookiepath($path) {

        $this->cookiePath = $path;
        $this->useCookie(TRUE);
        $this->saveCookie(TRUE);
    }

    /** 设置请求参数 parameters @param array GET or POST 的请求数据 @return void  */
    public function setParams($dataArray) {
        $this->params = array_merge($this->params, $dataArray);
    }

    /** 设置 basic http auth 域验证 @param string 用户名  @param string 密码  @return void */
    public function setAuth($username, $password) {
        $this->username = $username;
        $this->password = $password;
    }

    /** 设置最大跳转数 @param integer Maximum number of redirects @return void */
    public function setMaxredirect($value) {
        $this->maxRedirect = $value;
    }

    /** 添加多一个新的请求数据 @param string Name of the parameter @param string Value of the paramete  @return void  */
    public function addParam($name, $value) {
        $this->params[$name] = $value;
    }

    /** 添加 cookie 请求数据  @param string Name of cookie  @param string Value of cookie */
    public function addCookie($name, $value) {
        $this->cookies[$name] = $value;
    }

    /** 是否使用 curl, 默认 true, false 为使用 socket  */
    public function useCurl($value = TRUE) {
        if (is_bool($value)) {
            $this->useCurl = $value;
        }
    }

    /** 是否使用 cookie , 默认为 false  @param boolean Whether to use cookies or not  @return void  */
    public function useCookie($value = FALSE) {
        $this->useCookie = $value;
    }

    /** 是否使用 cookie , 以供下一次请求使用 @param boolean Whether to save persistent cookies or not @return void  */
    public function saveCookie($value = FALSE) {
        $this->saveCookie = $value;
    }

    /** 是否跟随 302 跳转 @param boolean Whether to follow HTTP redirects or not  */
    public function followRedirects($value = TRUE) {
        $this->redirect = $value;
    }

    /** 获取结果集  @return string output of execution */
    public function getResult() {
        return $this->result;
    }

    /** 获取最后一个返回的 headers 数组 */
    public function getHeaders() {
        return $this->headers;
    }

    /** 获取请求的状态码  */
    public function getStatus() {
        return $this->status;
    }

    /** 获取最后运行错误   */
    public function getError() {
        return $this->error;
    }

    /** 执行一条 http get 请求  */
    public function get($url, $data = array()) {
        return $this->execute($url, '', 'GET', $data);
    }

    /** 执行一条 http post 请求  */
    public function post($url, $data = array()) {
        return $this->execute($url, '', 'POST', $data);
    }

    /**
     * 使用当前的配置, 发送一条 HTTP 请求
     *
     * @param string URL of the target page (optional)
     * @param string URL of the referrer page (optional)
     * @param string 请求方法 (GET or POST) (optional)
     * @param array 请求数据, key 和 value 对应的数组 (optional)
     * @return string 请求的结果集
     */
    public function execute($target = '', $referrer = '', $method = '', $data = array()) {
        // Populate the properties
        $this->target = ($target) ? $target : $this->target;
        $this->method = ($method) ? $method : $this->method;

        $this->referrer = ($referrer) ? $referrer : $this->referrer;

        // Add the new params
        if (is_array($data) && count($data) > 0) {
            $this->params = array_merge($this->params, $data);
        }

        // Process data, if presented
        if (is_array($this->params) && count($this->params) > 0) {
            // Get a blank slate
            $tempString = array();

            // Convert data array into a query string (ie animal=dog&sport=baseball)
            foreach ($this->params as $key => $value) {
                if (strlen(trim($value)) > 0) {
                    $tempString[] = $key . "=" . urlencode($value);
                }
            }

            $queryString = join('&', $tempString);
        }

        // 如果 cURL 没有安装就使用 fscokopen 执行请求
        $this->useCurl = $this->useCurl && in_array('curl', get_loaded_extensions());

        // GET method configuration
        if ($this->method == 'GET') {
            if (isset($queryString)) {
                $this->target = $this->target . "?" . $queryString;
            }
        }

        // Parse target URL
        $urlParsed = parse_url($this->target);

        // Handle SSL connection request
        if ($urlParsed['scheme'] == 'https') {
            $this->host = 'ssl://' . $urlParsed['host'];
            $this->port = ($this->port != 0) ? $this->port : 443;
        } else {
            $this->host = $urlParsed['host'];
            $this->port = ($this->port != 0) ? $this->port : 80;
        }

        // Finalize the target path
        $this->path = (isset($urlParsed['path']) ? $urlParsed['path'] : '/') . (isset($urlParsed['query']) ? '?' . $urlParsed['query'] : '');
        $this->schema = $urlParsed['scheme'];

        // Pass the requred cookies
        $this->_passCookies();

        // Process cookies, if requested
        if (is_array($this->cookies) && count($this->cookies) > 0) {
            // Get a blank slate
            $tempString = array();

            // Convert cookiesa array into a query string (ie animal=dog&sport=baseball)
            foreach ($this->cookies as $key => $value) {
                if (strlen(trim($value)) > 0) {
                    $tempString[] = $key . "=" . urlencode($value);
                }
            }

            $cookieString = join('&', $tempString);
        }

        // Do we need to use cURL
        if ($this->useCurl) {
            // Initialize PHP cURL handle
            $ch = curl_init();

            // GET method configuration
            if ($this->method == 'GET') {
                curl_setopt($ch, CURLOPT_HTTPGET, TRUE);
                curl_setopt($ch, CURLOPT_POST, FALSE);
            }
            // POST method configuration
            else {
                if (isset($queryString)) {
                    curl_setopt($ch, CURLOPT_POSTFIELDS, $queryString);
                }

                curl_setopt($ch, CURLOPT_POST, TRUE);
                curl_setopt($ch, CURLOPT_HTTPGET, FALSE);
            }

            // Basic Authentication configuration
            if ($this->username && $this->password) {
                curl_setopt($ch, CURLOPT_USERPWD, $this->username . ':' . $this->password);
            }

            // Custom cookie configuration
            if ($this->useCookie && isset($cookieString)) {
                curl_setopt($ch, CURLOPT_COOKIE, $cookieString);
            }

            curl_setopt($ch, CURLOPT_HEADER, array('Accept-Language: zh-cn', 'Connection: Keep-Alive', 'Cache-Control: no-cache'));
            curl_setopt($ch, CURLOPT_NOBODY, FALSE);                // Return body

            curl_setopt($ch, CURLOPT_COOKIEJAR, $this->cookiePath);    // cookie 文件
            curl_setopt($ch, CURLOPT_COOKIEFILE, $this->cookiePath);    // cookie 文件

            curl_setopt($ch, CURLOPT_TIMEOUT, $this->timeout);       // Timeout
            curl_setopt($ch, CURLOPT_USERAGENT, $this->userAgent);     // Webbot name
            curl_setopt($ch, CURLOPT_URL, $this->target);        // Target site
            curl_setopt($ch, CURLOPT_REFERER, $this->referrer);      // Referer value

            curl_setopt($ch, CURLOPT_VERBOSE, FALSE);                // Minimize logs
            curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);                // No certificate
            curl_setopt($ch, CURLOPT_FOLLOWLOCATION, $this->redirect);      // Follow redirects
            curl_setopt($ch, CURLOPT_MAXREDIRS, $this->maxRedirect);   // Limit redirections to four
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);                 // 是否以 string 格式返回
            // Get the target contents
            $content = curl_exec($ch);

            // Get the request info
            $curl_info = curl_getinfo($ch);
            $header_size = $curl_info["header_size"];

            // 赋值结果集
            $this->result = substr($content, $header_size);

            $reader = explode("\r\n\r\n", trim(substr($content, 0, $header_size)));
            $this->status = $curl_info['http_code'];

            // Parse the headers
            $this->_parseHeaders(explode("\r\n\r\n", trim(substr($content, 0, $header_size))));

            // Store the error (is any)
            $this->_setError(curl_error($ch));

            // Close PHP cURL handle
            curl_close($ch);
        } else {
            // Get a file pointer
            $filePointer = fsockopen($this->host, $this->port, $errorNumber, $errorString, $this->timeout);

            // We have an error if pointer is not there
            if (!$filePointer) {
                $this->_setError('Failed opening http socket connection: ' . $errorString . ' (' . $errorNumber . ')');
                return FALSE;
            }

            // Set http headers with host, user-agent and content type
            $requestHeader = $this->method . " " . $this->path . "  HTTP/1.1\r\n";
            $requestHeader .= "Host: " . $urlParsed['host'] . "\r\n";
            $requestHeader .= "User-Agent: " . $this->userAgent . "\r\n";
            $requestHeader .= "Content-Type: application/x-www-form-urlencoded\r\n";

            // Specify the custom cookies
            if ($this->useCookie && $cookieString != '') {
                $requestHeader.= "Cookie: " . $cookieString . "\r\n";
            }

            // POST method configuration
            if ($this->method == "POST") {
                $requestHeader.= "Content-Length: " . strlen($queryString) . "\r\n";
            }

            // Specify the referrer
            if ($this->referrer != '') {
                $requestHeader.= "Referer: " . $this->referrer . "\r\n";
            }

            // Specify http authentication (basic)
            if ($this->username && $this->password) {
                $requestHeader.= "Authorization: Basic " . base64_encode($this->username . ':' . $this->password) . "\r\n";
            }

            $requestHeader.= "Connection: close\r\n\r\n";

            // POST method configuration
            if ($this->method == "POST") {
                $requestHeader .= $queryString;
            }

            // We're ready to launch
            fwrite($filePointer, $requestHeader);

            // Clean the slate
            $responseHeader = '';
            $responseContent = '';

            // 3...2...1...Launch !
            do {
                $responseHeader .= fread($filePointer, 1);
            } while (!preg_match('/\\r\\n\\r\\n$/', $responseHeader));

            // Parse the headers
            $this->_parseHeaders($responseHeader);

            // Do we have a 301/302 redirect ?
            if (($this->status == '301' || $this->status == '302') && $this->redirect == TRUE) {
                if ($this->curRedirect < $this->maxRedirect) {
                    // Let's find out the new redirect URL
                    $newUrlParsed = parse_url($this->headers['location']);

                    if ($newUrlParsed['host']) {
                        $newTarget = $this->headers['location'];
                    } else {
                        $newTarget = $this->schema . '://' . $this->host . '/' . $this->headers['location'];
                    }

                    // Reset some of the properties
                    $this->port = 0;
                    $this->status = 0;
                    $this->params = array();
                    $this->method = 'GET';
                    $this->referrer = $this->target;

                    // Increase the redirect counter
                    $this->curRedirect++;

                    // Let's go, go, go !
                    $this->result = $this->execute($newTarget);
                } else {
                    $this->_setError('Too many redirects.');
                    return FALSE;
                }
            } else {
                // Nope...so lets get the rest of the contents (non-chunked)
                if ($this->headers['transfer-encoding'] != 'chunked') {
                    while (!feof($filePointer)) {
                        $responseContent .= fgets($filePointer, 128);
                    }
                } else {
                    // Get the contents (chunked)
                    while ($chunkLength = hexdec(fgets($filePointer))) {
                        $responseContentChunk = '';
                        $readLength = 0;

                        while ($readLength < $chunkLength) {
                            $responseContentChunk .= fread($filePointer, $chunkLength - $readLength);
                            $readLength = strlen($responseContentChunk);
                        }

                        $responseContent .= $responseContentChunk;
                        fgets($filePointer);
                    }
                }

                // Store the target contents
                $this->result = chop($responseContent);
            }
        }

        // There it is! We have it!! Return to base !!!
        return $this->result;
    }

    /** 解析 header 信息 */
    private function _parseHeaders($responseHeader) {
        // Break up the headers
        $headers = $responseHeader;

        // Clear the header array
        $this->_clearHeaders();

        // Get resposne status
        if ($this->status == 0) {
            // Oooops !
            if (!eregi($match = "^http/[0-9]+\\.[0-9]+[ \t]+([0-9]+)[ \t]*(.*)\$", $headers[0], $matches)) {
                $this->_setError('Unexpected HTTP response status');
                return FALSE;
            }

            // Gotcha!
            $this->status = $matches[1];
            array_shift($headers);
        }

        // Prepare all the other headers
        foreach ($headers as $header) {
            // Get name and value
            $headerName = strtolower($this->_tokenize($header, ':'));
            $headerValue = trim(chop($this->_tokenize("\r\n")));

            // If its already there, then add as an array. Otherwise, just keep there
            if (isset($this->headers[$headerName])) {
                if (gettype($this->headers[$headerName]) == "string") {
                    $this->headers[$headerName] = array($this->headers[$headerName]);
                }

                $this->headers[$headerName][] = $headerValue;
            } else {
                $this->headers[$headerName] = $headerValue;
            }
        }

        // Save cookies if asked
        if ($this->saveCookie && isset($this->headers['set-cookie'])) {
            $this->_parseCookie();
        }
    }

    /** 去除所有 header 信息 */
    private function _clearHeaders() {
        $this->headers = array();
    }

    /** 解析 COOKIE */
    private function _parseCookie() {
        // Get the cookie header as array
        if (gettype($this->headers['set-cookie']) == "array") {
            $cookieHeaders = $this->headers['set-cookie'];
        } else {
            $cookieHeaders = array($this->headers['set-cookie']);
        }

        // Loop through the cookies
        for ($cookie = 0; $cookie < count($cookieHeaders); $cookie++) {
            $cookieName = trim($this->_tokenize($cookieHeaders[$cookie], "="));
            $cookieValue = $this->_tokenize(";");

            $urlParsed = parse_url($this->target);

            $domain = $urlParsed['host'];
            $secure = '0';

            $path = "/";
            $expires = "";

            while (($name = trim(urldecode($this->_tokenize("=")))) != "") {
                $value = urldecode($this->_tokenize(";"));

                switch ($name) {
                    case "path" : $path = $value;
                        break;
                    case "domain" : $domain = $value;
                        break;
                    case "secure" : $secure = ($value != '') ? '1' : '0';
                        break;
                }
            }

            $this->_setCookie($cookieName, $cookieValue, $expires, $path, $domain, $secure);
        }
    }

    /** 设置 cookie , 为下一次请求做准备 */
    private function _setCookie($name, $value, $expires = "", $path = "/", $domain = "", $secure = 0) {
        if (strlen($name) == 0) {
            return($this->_setError("No valid cookie name was specified."));
        }

        if (strlen($path) == 0 || strcmp($path[0], "/")) {
            return($this->_setError("$path is not a valid path for setting cookie $name."));
        }

        if ($domain == "" || !strpos($domain, ".", $domain[0] == "." ? 1 : 0)) {
            return($this->_setError("$domain is not a valid domain for setting cookie $name."));
        }

        $domain = strtolower($domain);

        if (!strcmp($domain[0], ".")) {
            $domain = substr($domain, 1);
        }

        $name = $this->_encodeCookie($name, true);
        $value = $this->_encodeCookie($value, false);

        $secure = intval($secure);

        $this->_cookies[] = array("name" => $name,
            "value" => $value,
            "domain" => $domain,
            "path" => $path,
            "expires" => $expires,
            "secure" => $secure
        );
    }

    /** cookie  数据集编码  */
    private function _encodeCookie($value, $name) {
        return($name ? str_replace("=", "%25", $value) : str_replace(";", "%3B", $value));
    }

    /** 把正确的 cookie 传输给当前请求 */
    private function _passCookies() {
        if (is_array($this->_cookies) && count($this->_cookies) > 0) {
            $urlParsed = parse_url($this->target);
            $tempCookies = array();

            foreach ($this->_cookies as $cookie) {
                if ($this->_domainMatch($urlParsed['host'], $cookie['domain']) && (0 === strpos($urlParsed['path'], $cookie['path'])) && (empty($cookie['secure']) || $urlParsed['protocol'] == 'https')) {
                    $tempCookies[$cookie['name']][strlen($cookie['path'])] = $cookie['value'];
                }
            }

            // cookies with longer paths go first
            foreach ($tempCookies as $name => $values) {
                krsort($values);
                foreach ($values as $value) {
                    $this->addCookie($name, $value);
                }
            }
        }
    }

    /** 匹配域名 */
    private function _domainMatch($requestHost, $cookieDomain) {
        if ('.' != $cookieDomain{0}) {
            return $requestHost == $cookieDomain;
        } elseif (substr_count($cookieDomain, '.') < 2) {
            return false;
        } else {
            return substr('.' . $requestHost, - strlen($cookieDomain)) == $cookieDomain;
        }
    }

    /** 给当前操作做记号用的 */
    private function _tokenize($string, $separator = '') {
        if (!strcmp($separator, '')) {
            $separator = $string;
            $string = $this->nextToken;
        }

        for ($character = 0; $character < strlen($separator); $character++) {
            if (gettype($position = strpos($string, $separator[$character])) == "integer") {
                $found = (isset($found) ? min($found, $position) : $position);
            }
        }

        if (isset($found)) {
            $this->nextToken = substr($string, $found + 1);
            return(substr($string, 0, $found));
        } else {
            $this->nextToken = '';
            return($string);
        }
    }

    /** 设置错误信息 */
    private function _setError($error) {
        if ($error != '') {
            $this->error = $error;
            return $error;
        }
    }

}

?>